Applicant's assignee has already described in its French patent applications Nos. 81-07144 and 83-05422, the use of such ferrules for making optical connections and the different steps for their preparation for positioning and centering the fiber in the ferrule, especially with respect to the conical wall which is set back with respect to the end of the fiber.
To make the optical connections provision was made in the earlier documents to use an abutment body, especially spherical, with axial opening to receive the axial projection of the ferrule, the abutment body defining a bearing contact surface with the conical annular wall of the ferrule, so that during any relative movement of the bearing surfaces in contact, the end of the fiber at the level of the end surface of the projection of the ferrule is held at a constant predetermined distance from the center of the abutment body.
The abutment body, in the shape of a sphere for the connection of two optical fibers or a semi-sphere for the connection of an optical fiber to an electroluminescent diode, must have great dimensional precision, generally on the order of + or -3 um.
It is expensive to make spheres or semi-spheres of such precision.